Fixed #23120 -- Updated GeoDjango tutorial for migrations workflow.
Fixed #23079 -- Added data loss issues to those that will be backported to LTS.
Forwardported 1.6.6 release notes for refs #20292.
Make detect_soft_applied exit correctly on non-create migrations
Fix soft_applied in a way that doesn't break tests
Fixed a typo in the admin documentation.

The 'app' subpackage does not exist, should be 'app'.
Fixed #23101: Prefer doing deletes before creates in autodetector.

Makes declined or missed renames still work (but drop data).
Fixed #23090: Document and enforce not double-squashing migrations
Fixed #23127: south_migrations note in docs
Fixed #23092: Squashing handles external dependencies
Fixed #23129 -- Added 'true' and 'false' to `NullBooleanField`.

JavaScript serializations of forms will sometimes render the boolean
values as the strings 'true' and 'false', in lower case. Rather than
repeat boilerplate in the JavaScript to circumvent this, it seems
reasonable to allow Django to understand the lower-case versions of the
booleans.
Fixed #7220 -- Allowed AbstractBaseUser.last_login to be null.